#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<math.h>
int main()
{
    int n = 0.0;
    int m = 0;
    while (scanf("%d %d", &n, &m) == 2)
    {
        double sum = 0.0;
        double _n = n;
        int _m = m;
        while (_m)
        {
            sum += _n;
            _n = sqrt(_n);
            _m--;
        }
        printf("%.2f\n", sum);
    }
    return 0;
}